Have you checked that the ports are open between the ESX host and the License server?
Whilst the ESX firewall may permit the client outbound, the ports on the physical network may not be open, posibly due to an internal change on the firewall's etc..
Have you tried
1. restart flexlm license service
2. restart virtual center server (if your license server is on the vc server.)
Frank Brix Pedersen
Ten other servers are able to connect and get their licenses, and they have no problems. There are no firewalls between the servers, in any case.
I've tried restarting the services, but I have not yet rebooted the server. I guess I'll give that a shot when I get the chance.
The solution was to shut down Virtual Center and, while that's down, restart mgmt-vmware, vmware-vpxa, and vmware-vmkauthd on the affected host, then restart VC.
What is vmkauthd?